PALMER — Authorities here arrested four town residents and seized dozens of bags of heroin as part of an ongoing drug investigation.

Palmer Police Sgt. Christopher Burns said the suspects were taken into custody around 10 p.m. Tuesday after investigators seized 400 bags of heroin.

Michael Barrett, 31, Ryan Wilson, 21, and Kristin Schuelke, 21, were each charged with heroin possession and possession of a class D drug. Timothy Laviolette was charged with heroin possession with intent to distribute and possession of a class D drug.

Marijuana is the most common class D drug in Massachusetts.

The suspects were released with return court dates after arraignments Wednesday in Palmer District Court.